I am aware of that. I often use the trick to register multiple times on the same website. Also, you can use (+) to create unlimited siblings of your gmail address. Helpful to keep track of spams.

I don't think it works with spam anymore - except for naive spammers, they are very aware of this trick.

It IS for organising legitimate incoming mail though.

I wonder how many people know about this? And how exactly using '+something' helps in filtering spams?